Not sure what you want the drawing shows all those things Maybe just a regular detailed floor plan will help.

Thanks for the suggestions, Nancy! Putting the dining table on the side like that helps with the "choke point" that we currently get between the table and wall in the centre of the room. Any suggestions for what you would do with the extra space towards the kitchen, since the dining table is no longer in that space? I agree about the bench: We were thinking about getting this table: https://ca.transformertable.com/pages/the-dining-set which has a matching extending bench to go along the window. I don't want any built in units on the ends because I want to be able to extend the table across the majority of the room when a lot of company is over.

I would create a "foyer" by floating a 3-seat sofa or a reversible chaise sofa facing the two windows with a flat screen TV on a low credenza. Hang the clock on the wall opposite its present location. Flank the large front window with a pair of fabric armchairs, a new side table and a table lamp. A new rug should be at least 2 feet wider than the new sofa. For proper installation of a dining chandelier, your table will need to sit under the current fixture. Try doing that to see what you can achieve. Do you want to hire an electrician to remedy the offset? You can probably find a paired semi-flush and a pendant or chandy for both your ceiling lights and maybe the kitchen too. Once you find the seating and rug, we can find a new, brighter paint color to really bring this room out of the shade!

Like the corner with windows on two sides. Temperature aside, the one negative that comes to mind to all that light is the potential glare on the tv. You might want to put whatever tv you get on a portable stand so you can adjust its positioning as needed. This is a modern space so a portable stand should fit in well. Some have more position options than others. https://www.google.com/search?q=portable+tv+stands&client=firefox-b-1-d&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjko7Ku36zqAhUfmXIEHY-OC0QQ_AUoAnoECA0QBA&biw=1366&bih=654 A sectional will just about fill up your seating area and you will be extremely limited with regard to placement and very limited as to other seating. Large pieces could crowd your space making it fee smaller than necessary. IF a sectional is torn or stained -- any issue that cannot be fixed -- then that is a lot of costly seating you'd need to replace to get rid of a problem. When you furnish your study/den, you might consider choosing chairs that could be brought out to the living area when you have guests so you could have a less crowded space the rest of the time. Draw, to scale, your space and then draw, to scale, the furnishings you are considering for it so you cut out the pieces of furniture and see what will or will not fit the way you want. For tv watching, I have a personal preference for size appropriate swivel rocker recliners.